All-terrain amphibious vehicles which employ endless tracks as means for propulsion are widely known in the art. However, there are several problems associated with the use of endless propulsion tracks which greatly reduce the performance and maneuverability of the vehicles, both on land and in the water.
In many of the known designs, the forces necessary to propel the vehicle are generated by the endless track by virtue of a series of projections or cleats extending substantially across the width of the outer surface of the track. The cleats are generally oriented perpendicular to the path of travel of the endless tracks. Thus, as the endless track is rotated, the action of the cleats on the terrain generates sufficient propulsion to provide for forward motion. However, in muddy or loose soil, these cleats tend to carry the mud or loose soil onto the track thus increasing the weight of the propulsion mechanism and decreasing its efficiency. In addition, the propulsion forces generated by the cleats are generally in a rearward direction, and provide little or no lateral stability to the vehicle.
U.S. Pat. No. 3,311,424 to Taylor, issued Mar. 28, 1967 discloses a track device comprising a belt driven soft roller. One embodiment of the Taylor device discloses a clear arrangement in the form of a series of chevrons which extend across the width of the belt. While this cleat arrangement provides propulsion forces containing vector components in a lateral direction with respect to the vehicle, these lateral components are directed inwardly towards the center of the cleat and, thus only marginally affect the lateral stability of the vehicle. In addition, mud and loose soil may collect at the center point of each of the chevron cleats as the track moves over the terrain.
U.S. Pat. No. 2,091,958 to Braga issued on Sept. 7, 1937, discloses a boat employing an endless propulsion belt. Braga further employs a series of stationary baffles which remove water which has accumulated on the surface of the belt. It should be noted that until the boat has reached cruising speed, the water line is above the entire belt mechanism. Since the motion of the upper surface of the belt is in a direction opposite to that of the lower surface of the belt, a considerable amount of drag is created.
Further, in many of the know all-terrain amphibious vehicle designs, difficulty is experienced in initially providing proper tension for the endless tracks and in maintaining proper tension over extended period of usage.
Also, the prior art endless track designs all suffer from the disadvantage that failure of one of the endless tracks on either side of the vehicle substantially totally disables the vehicle.
The present invention is directed to overcoming the problems as set forth above.